Why does my egg contain two yolks?

We occasionally find jumbo eggs in our nest boxes, but I’m pretty sure this is the largest one we’ve ever seen! Those are ordinary-sized (large) eggs on all sides of the jumbo egg, getting ready to be turned into a homestead lunch.

If you’ve kept chickens for long, you probably know why the jumbo eggs show up — they’re so big because they contain double yolks. Usually, a hen releases a new yolk to start the egg-making process about an hour after the previous egg has been laid. But sometimes she accidentally releases two yolks close together, and those yolks end up getting enclosed in the same shell, create a double-yolker.

This type of minor egg-laying problem is most common among pullets just coming into laying and among old hens coming to the end of their productive life span. Our jumbo egg showed up in our chicken tractor, where our only older hen lives, so I suspect the old girl is the culprit.

According to the internet, one egg in a thousand contains two yolks, but you’ll never see a double-yolker if you stick to commercially-raised eggs. The industry candles each egg and discards double-yolkers, even though the issue is merely a cosmetic problem. I’m not sure if that’s a reason to raise your own laying hens, but it’s an interesting factoid! (And the delicious taste and high nutritional value of pastured eggs definitely make them worthwhile to raise at home.)